Your HP is directly correlated to your Hit Dice, so it’s one of the many ways that Wizards of The Coast decided to separate the classes in their different roles. Your class will have one of four types of hit dice:

d6/lvl for squishy casters (Sorcerers and Wizards) d8/lvl for scrappy midliners (Bards, Clerics, Druids, Monks, Rogues, and Warlocks) d10/lvl for the frontline damage (Fighters, Paladins, and Rangers) d12/lvl for Barbarians, because Barbarians shouldn’t be able to die, they’re far too angry.

For the sake of clarity, whenever I refer to something as dXX, that’s the dice you should be rolling. For example, a d20 is a 20 sided die, a d8 is your 8 sided die, etc. For most players this might seem redundant, but I guarantee there’s at least a few newer players that just had epiphanies. With that out of the way, let’s get into it!

Hit Dice At Level 1

When you’re making your character, Hit Dice are not too difficult. To find health at Level 1 take the max roll for your hit dice (for a d10 that’s 10) and add your constitution modifier. For our level 1 Fighter with a constitution of 12 (+1), his starting hit points would be 11.

Hit Dice At Level 2 (And Beyond)

When you level up things will begin to get more complicated. And it’s mostly because now you have a choice. Gamble for higher HP by rolling your classes Hit Dice, or take the safe, but potentially lower, route of the adjusted median. Here’s what both options would look like for that Fighter as he levels up to Level 2: Adjusted Median: To find your classes adjusted median all you have to do is take that class’s Hit Dice, half it, and add one. For a Fighter with a Hit Dice base of d10, halving it would leave you with 5, plus one is 6. Therefore, d10 classes have an adjusted median of 6, easy! At level up you take that adjusted median and add your constitution modifier, which for our case is +1, so our Fighter would gain 7 health on a levelup. Rolling for Health: This is by far the riskier strategy. Instead of taking the adjusted median you roll your Hit Dice, and whatever number comes up is the number you add your constitution modifier to. If you roll a 1? Sucks, enjoy your 2 health on level up. If you roll a 10? Nice, you just effectively gained 4 extra health than you would’ve by playing it safe. Needless to say, rolling for health is almost never worth the risk. But the next couple paragraphs will take a much deeper look at Hit Dice and the actual math behind whether or not you should be rolling for health.

The Game Theory Behind Hit Dice Rolls

Take the safe above-average roll, or shoot for something higher. For any class on a d6, or d8 (with adjusted medians of 4 and 5 respectively) never take the roll. There is simply not enough to gain and too much to lose. You wet napkins will need every hit point you can get. For d10’s and d12’s, you lucky bastards, it isn’t the worst idea to take the roll. And here’s why. Essentially, with the higher hit dice values you have better odds of gaining significant hit points via roll; d6 classes have a 1/3 (.33) of gaining up to 2 HP, d8 have 3/8 (.37) of gaining up to 3 HP, d10 have 2/5 (.4) of gaining up to 4 HP, and d12 have 5/12 (.42) of gaining up to 5 HP. So for a Barbarian with the best odds, a little under half the time you level up you will be experiencing gains if you decide to roll. But here’s where the game theory comes in. Is it worth it to take the risk? Let’s say you play this Barbarian until level 13. And because you’re using a perfect d12 you roll one of the sides each level up. Our Barbarian has a constitution of 10 (+0) to make the math easier to explain, so here is the what level up would look like with statistically average rolls (left) vs. taking the adjusted median (right): You can see that even if the end, scores are relatively close. The chance of spending some levels basically a level behind in HP makes the risk a really difficult one to take. Still, don’t let me stop you from being the chaotic little goblins we so often want to be. Maybe you’ll defy the odds and be the godly level 13 Barbarian with 156 health. Like with most things in D&D, a little luck can go a long way. But remember that even with the best possible odds you still end up a little behind the person who played it safe.

Hit Dice & Multiclassing

The most confusing exception in Hit Dice is Multiclassing. Let’s say our fighter opts not to roll, and is now level 4 (with an HP of 32) about to level up to level 5. He reads this article, likes the idea of more HP vs less, so he talks to his DM and decides to multiclass into Barbarian. His strength is high enough, and it makes sense for the character, so he levels up. What’s his total level? Even though we would denote it as Fighter 4 Barbarian 1, he’s still a 5th level character in total. And gets the increased proficiency bonus that comes with it. As for configuring health, you do the same as if you had been taking barbarian this whole time. Ao either roll or take the adjusted median, and add your constitution. Our cautious player opts out of rolling (coward) and now has 40 HP. Essentially, Hit Dice are a way to represent the very complex and nebulous idea of ‘Health’. And I promise they make more sense as you use them. The easiest way to get a good hang of how they work is to roll up a new character, so let’s get rolling!

Hit Dice Live Example

The glories of hit dice don’t end at leveling up! You can use them during short rests to regain health, and make that prolonged dungeon a bit more survivable. We’ll take our level 5 character from earlier, he has 4d10+1d12 hit dice (4d10 from 4 levels of Fighter, and 1d12 from 1 level of Barbarian). He takes a spear to the chest fighting a skeletal mob, and his group decides to take a small break to let him walk it off. They set up camp for the hour, and you now get the pleasure of deciding how many hit dice to use. The spear did 16 damage which you don’t want to carry into the next room of the dungeon. But at the same time you don’t know what else there could be in the dungeon, and you doubt that the skeletons were the final boss. Before you roll, you have to declare how many dice you intend to use. So you play it safe with 1d10+1d12, and recover 1d10+1d12+ our con modifier of +1 for each die you roll. This leaves you with 3d10 Hit Dice to use on your next short rest. Remember, don’t be too frugal. Your hit dice refresh after a long rest. Down times lasting an hour are pretty rare, and dead characters can’t use hit dice as their rest is eternal.

What Does “More Health” Look Like?

This is a hard question to answer in-game. You didn’t gain mass or size making the hits less damaging by comparison. You didn’t get better armor that protects you from the hits… so why are you harder to kill?
The way I’ve chosen to think about it is that your character gets better at doing whatever it is makes their class take less damage. For example, Monks might get better at diverting the force of a blow. Or Wizards have greater concentration, so the damage feels like less, anything like that. The important thing to recognize is that as your HP goes up, the same move will do proportionately less damage. So having the explanation behind gaining health on a level up might just be that your character is better at dealing with the hurt. At the end of the day, the character sheet is just the way that we as players visualize the complex goings-on of our characters. The numbers don’t actually exist in their world. More than anything, have fun with it. Talk to your DM, and be ready to roll some dice! D&D5e is a relatively streamlined system. But as you get into the crunchy meat and potatoes of the game, it’s best to grab your PHB and get ready to rumble.